"The public is going to be stunned when all hell breaks loose. They're going to ask, 'Why didn't we know?'" he said to conservative Post blogger Jennifer Rubin. He also said he believes that the U.S. could have had a chance to change the regime after the disputed 2009 Iranian presidential elections, which sparked widespread protests. "We could have been in the position during the Green Revolution [to oust the mullahs] if we had publicly condemned the regime, brought in the U.N. and rallied the world community behind the dissidents. We didn't do that," he said.

At the time of the elections, President Barack Obama said he had "deep concerns" about the elections and subsequent violence, but said direct involvement by the U.S. would not be "productive, given the history of U.S.-Iranian relations." Shirin Ebadi, an Iranian human rights activist and dissident who won the Nobel Peace Prize in 2003, had no complaints about Obama's response at the time of the disputed elections. "I respect his comments on all the events in Iran, but I think it is sufficient," she said.

Former Massachusetts Gov. Mitt Romney said in Tuesday night's Republican presidential debate that he favored "crippling sanctions" and indicting Iranian President Mahmoud Ahmadinejad at the United Nations for inciting genocide. Former House Speaker Newt Gingrich said he would take military action against Iran if it led to regime change.

Western powers imposed sanctions Monday focused on cutting off Iran from the international financial system. The International Atomic Energy Agency released a report earlier this month stating that "Iran has carried out activities relevant to the development of a nuclear device."